Product was successfully added to your shopping cart.
0item(s)

You have no items in your shopping cart.

Previous

Apollo-7 MTM

Previous

S2000 MTM

Helix Dome MTM

Quick Overview

High end 7" MTM.


* This kit ships for free *

$289.70

Availability: Out of stock

Details

June 14, 2023:  It's highly recommended that you order the flat pack at the same time you order the speaker kit.   A lot of people that try to make their own cabinets have trouble cutting the port holes on the back and end up needing to order the custom flat packs a few months later.  From now on I will have to charge extra money on the flat packs if you order them later because of the extra packaging material needed.

Product Notes: 

The Helix Dome MTM makes for a great full range monitor style speaker using one of Jeffs favorite dome tweeters. It uses a custom high end woofer with a 3 layer cone. The middle layer is a hexagon matrix similar to a honeycomb that gets 'sandwiched' between the two other layers to make for a strong light weight cone. I'll upload some more photos soon. I was able to get a smaller batch of these made at first to see how people liked them, but the price shown on woofers might have to go up a bit when they're made again. The list price is supposed to be much higher. That may or may not change the price of the kit later. 

 

 

Product Highlights:

  • Uses a hidden gem of a tweeter:  The SB Acoustics SB29SDAC.
  • High end woofers with 3 layer sandwiched hexagon matrix.
  • Smooth and detailed sound.
  • Can be used as a center channel by laying on it's side.
  • Timbre matched to the single woofer version.

 

Minimum order is 2 speakers: If you ordered one in the past and need one for a center, please contact me. Kits are sold as full kits, sorry no substitutions or subtractions. Don't forget binding posts, terminal cups, or speaker spikes if you need them because they can be shipped for free with any kit or flat pack purchase.

Shipping Note: Most speaker kits currently ship for free, but flat packs normally do not.  We try to get your order packaged and shipped in 5-8 days depending on how many orders have come in.  Please read the 'Frequently Asked Questions' section for more information.

  1. Serious High-End Performance review by UtopiaNemo on 7/13/2023
    Design
    Performance
    Value

    I bought these for my main L/R in my system (after way too much research). They replaced my beloved Epos Epic 2s, which, while incredible speakers for the price, would start to lose their composure when really pushed. I was looking for a speaker that could handle high SPL without losing their dynamics, but had wider dispersion (and hence a wider soundstage) and more refinement than the more HT-centric that DIYSG offers. Also, this being DIY, I was looking for the best dollar: performance ratio I could possibly get with those criteria.

    After literally years of research and indecision, I went with the Helix MTMs. As in another customer review here, Erich suggested the Helix over the Apollo because my preference was a little bit more refinement over a little bit more SPL. Did they meet my standards? Absolutely they did.

    The kit was easy to put together, and like others I recommend the crossover kit. The finish work was harder than I anticipated, but I’m an electrician by trade. At my limited skill level (and a lot of sweat equity), I was able to get a look that most visitors have been pretty impressed with.

    But you’re really reading this to find out about the sound, aren’t you? Well, the Helix sounds amazing. Extremely balanced across the frequency range, great imaging and soundstage, and well composed and dynamic at all volumes in my 15’x20’x8’ room. I recommend use with subs for music with extremely low frequencies, such as organs, dubstep, and modern rap, but they’ll do fine unassisted with anything else.

    As happy as I was with the Helix, I haven’t compared them with anything else in my room. I recently hosted a GTG with some folks who listen to a lot of high dollar gear, and they were extremely impressed with the speakers. They have the ability to play loud while still revealing subtle details in the recordings.

    I do have one caveat to the Helix MTM, and that is that they have the typical narrow vertical dispersion pattern of an MTM. I feel the extra muscle in presentation is worth it, but YMMV. I’m not sure I’d use a Helix MTM lying on its side for a center, but the phantom center is so good, I’m not missing it. I may purchase five of the MT versions to replace my remaining surround channels, with the last MT for a center, but I’m happy enough with these as-is that I’m in no hurry to modify what I’ve got. As for the vertical dispersion, as long as you’re not alternating between sitting and standing in the middle of a music/movie session, there’s no problem. And actually, even if you choose to sit with the tweeter a bit above or below the ear, it’s still fine. Just pick a seat and stay there. Oh, and get the Helix. They’re freaking awesome.

  2. A legitimate Hi-Fi dome tweeter option from DIYSG review by Brian6751 on 12/21/2019
    Design
    Performance
    Value

    Shout out to the man, the myth, the legend, Mr. Jeff Bagby!

    I FINALLY finished building his Helix Dome MTM design for LCR’s and I am shocked at how good they sound. I thought the MT version was a giant killer for its price but the MTM takes it to another level. I have been staying up way too late the last few nights with a huge Joker-ass grin on my face. Lol

    I mostly listen to two channel and consider myself pretty picky when it comes to speakers. I know within a few minutes wether I like a speaker or not. I’ll usually examine the highs first, then the bass, and finally the midrange. They don’t all have to sound the same, they just have to have proper driver integration and sound good!

    The Helix Dome MTM is definitely one of those speakers that I knew I liked right away. The driver integration is spot on. That tweeter is smooth as silk with tons of detail, air and excellent off axis ability. The bass is surprisingly full and detailed and extends plenty low for my music tastes. The midrange is as good as any I have heard in a two-way speaker of this size and up to around the $2k range. That woofer does a great job of giving the mids some density without getting muddied up when it has to jam out the lower frequencies at the same time.

    This is a lush, well designed, HiFi sounding speaker and definitely gets my recommendation for two channel or someone with a mixed use system with a priority on music listening. Especially if you're looking for something other than the usual horn loaded designs. (Nothing against horns. Put your torches away lol)

    What you have here is two great drivers that compliment each other combined with the crossover wizardry of Jeff Bagby. Knowing that, you would have to think they sound amazing and they do!

    Thank you Jeff (and Erich at DIYSG) for sharing another incredible design and making it possible for us to enjoy great speakers without selling a kidney!



    [url]https://www.diysoundgroup.com/home-audio-speaker-kits/home-audio-series/helix-speaker-kits/helix-dome-mtm-kit.html[/url]

  3. Fantastic review by Darrel on 11/19/2019
    Design
    Performance
    Value

    If you are on the fence of buying these--hop off the fence and press the buy button. These punch WAYYY above their price point, and I could not be any happier with my purchase.

    The best way I can describe these speakers is clean and clear without being sterile.

  4. Great LCR (The 3 Amigos) review by Rick on 6/3/2019
    Design
    Performance
    Value

    This is my second go-round with DIYSG and I have yet to be disappointed. I wanted matching LCR for my fronts and debated for a bit on whether to buy these or the Apollos. After speaking with Erich for a bit, he convinced me to purchase the Helix's as they would be very much on par with the Apollo's. Im sure the Apollos are great, but if you can live without the extra 4hz of low end the Apollos produce, I don't think you will be disappointed at all with purchasing the Helix's.

    I built my own boxes because I needed a front ported design. My speakers need to be in the corners of my room and its been known to get kinda boomy with rear ported speakers. I ended up placing the front port on the bottoms. The dimensions for the ports are .625 inches tall by 9.5" wide (width of baffle) by 6" deep and are flared in the front. I have them filled with about half a pillows worth of polyfill. Jeff Bagby did a great job designing these speakers, they sound wonderful, Thanks Jeff! They sound great with music and sound even better for HT use. I mainly use these for HT and gaming and I am very pleased. The Left to Right swings in sound are flawless and that bass is tight and accurate. This is exactly what I was looking for. I can only imagine what they will sound like once I get myself a good subwoofer.

    They have replaced a pair of Fusion-12 tempests and a quad center. TBH, I really cant tell a difference in bass reproduction from the Tempest to the Helix. The Helix do 40 hz really well. To compare the dome tweeters to the compression drivers of the tempest, I would have to say that the compression drivers are clearer, but not by much. The compression driver has a slightly better phantom center when running 2 channel, but not super noticeable, the helix does a nice phantom center as well. But, where the dome takes that CD is in vertical dispersion. I feel that the CD loses that soundstage if you stand up form your main LP. If you stand form your LP with the dome, your listening image doesnt disappear as much. That is about the only big difference I can think of. My speakers before the tempests had dome tweeters and I would get ear fatigue listening for an extended periods. The Helix's domes dont give me fatigue, which is nice. No one likes to feel like theyre getting punched in the ears. The domes for the Helix's are really nice, I have been very happy with them.

    Thanks Jeff for designing such a wonderful speaker. Im sure I will get many years of joy from these.

    Thanks Erich once again for your help, you have been great in answering all my oddball questions. Im sure you also laugh yourself to sleep every night knowing that we all have to unbox the overflow of styrofoam bits that ever so perfectly keep our precious speakers kits intact when you ship them to us. I salute you sir, you are a master at your packaging craft.

  5. No Need For A Sub with this kit review by Kenneth on 11/28/2018
    Design
    Performance
    Value

    After spending many hours listening to this kit I removed my sub. And I can't tell its gone. They even sound better with out the sub . https://www.youtube.com/watch?time_continue=19&v=RqGE-PWDa-o https://www.youtube.com/watch?v=sZ3v4jw6sb8

  6. Best MTM Kit out there review by Kenneth on 11/23/2018
    Design
    Performance
    Value

    First of all where can you buy a speaker kit that you can approach the seller (Erich) and the designer ( Jeff Bagby)? I researched this kit for months and contacted Erich and Jeff multiple times before I bought this kit. High quality custom woofers worth every penny and then some. Kit was packed extremely well. The printed circuit board made for a professional looking cross over. Another thing well worth getting with your kit. First sound impressions. WOW listening in 2 channel stereo playing vinyl (July Talk) at 1/2 throttle for 10 min. I couldn't resist and had to go 3/4 throttle and they sound great .....Vocals sharp and clear and bass nice and tight . They hit the highs and lows on target . Thank's Erich and Jeff I will have many hours of listening pleasure on these great speakers.

  7. Great first DIY build review by Ryan on 6/26/2018
    Design
    Performance
    Value

    I built the Helix MTM speakers over a two day period. The flat packs are cut with extreme precision making assembly quick and easy. I only had to use 3 clamps to put the enclosures together. After I built the speakers I had some strange distortion when listening to certain songs, Erich took a fair amount of time answering my questions and helping me get the problem resolved ( it was my source not the speakers). So after finding another source that didn't distort I was able to sit back and listen. The speakers are very open and detailed with good imaging and sound stage. I will be writing up a more detailed review with measurements on AVS forum in the next few weeks.

Write Your Own Review

How do you rate this product? *

  1 star 2 stars 3 stars 4 stars 5 stars
Performance
Value
Design

Image not uploaded yet

 

Speaker Kit Information

 

  Model:      The Helix Dome MTM
  Designer:      Jeff Bagby
  Frequency Response:      40hz - 20khz (+/-3db)
  Power Range:      10 - 150 watts
  Sensitivity:      91db - 2.83v/1m
  Impedance:      4 Ohm
  Tweeter:      SB Acoustics SB29SDAC
  Midrange:      N/A
  Woofer:      Denovo 7" Hexcore woofers
  Enclosure Type:      Ported
  Dimensions:      9.5" W x 23.5" H x 13" D
  Kit weight (no cabinet):      N/A
  Assembled weight:      Varies

Price Break Down:

2 - 7" Denovo Hexcore woofers: $188.40
1 - SB Acoustics SB29SDAC-C000-4 tweeter: $50.10
1 - Set of crossover parts: $30.70
2 - 2" adjustable ports: $6.98
1 - 3/4" thick CNC cut front baffle:  $12
1 - Set of screws and gaskets:  $1.50
 
 

Packaging Material: $4.00

Paypal Fee: $9.40

Retail Cost: $303.08

Discount Cost: $289.70 and shipped for free.

Please read the 'About Us' section for more information on pricing structure and quality parts used.

Specific Helix Dome MTM Assembly Notes:

Your enclosure should be built with 3/4" thick material with two horizontal "window pane" style braces to the dimensions listed.  It is recommended that you lightly stuff your enclosure with polyfill without blocking the ports. The original port is telescopic with an extension.  You don't need the extensions at all, just the inner section.  I will likely start shipping them without the extension tube so it doesn't cause any confusion.

 

Recommended Tools and Supplies:

  • Quality wood glue like TiteBond.
  • At least 2 clamps 24" wide or bigger.  
  • Soldering Iron and solder unless there is an optional assembled crossover for your kit.
  • Wire cutters
  • Screwdriver
  • Drill to predrill all screw holes.
  • Sanding block or power sander.
  • About 8' of speaker wire to connect your woofers and tweeter to the crossover board.

 

General Tips:

    Crossover Assembly: 

  • VERY IMPORTANT - Inductors are the parts that look like small rolls of copper wire. Notice that the two ends of wire are silver and have been 'tinned' with solder. Those are the parts of the inductor that you should be soldering to, so don't cut it off to get to the copper colored portion.  Inductors should not be installed directly next to each other on your board.
  • None of the crossover parts have a positive or negative side so it doesn't matter which way they are facing when you assemble your crossover. 16-18 gauge wire is thick enough to use for your crossover or to go from your crossover board to the woofer or tweeter.
  • Your crossover can be assembled on a thin piece of MDF or pegboard if the kit doesn't come with a circuit board.
  • It doesn't matter where you put the crossover inside your speaker.  You could mount it on the outside if you wanted to.  
  • Normally you wire red wires to positive and black wires to negative.  If (and only if) your crossover schemtaic has a note saying 'Inverted Polarity', that means you need to connect the negative from the crossover to the positive on the tweeter and positive from the crossover to the negative on the tweeter.  This is only done on some tweeters, not woofers.
  • Click Here for a good assembly video by Matt Grant.

     

     Screws and Gaskets:

  • Predrill all screw holes with a bit that's slightly smaller than your screws to prevent the wood from splitting.  Most screws are #8 panhead and you can use a 7/64" or 1/8" drill bit.  Overnight Sensations use a #6 panhead so you can use a 3/32" bit.
  • VERY IMPORTANT:  Protect your woofer or tweeter when installing screws because you don't want the screwdriver to slip and puncture one of your components....that will ruin your day!  Consider putting your free hand next to the screw to cover up the edge of the woofer or tweeter.
  • If your kit comes with gasket tape, it should be applied to the back of the waveguide. Peel the paper off the back to expose the sticky side and slowly work it around the perimeter on the back side of the part.  Some woofers will need gasket tape as well.

   

     Stuffing or Lining the Speaker Cabinet:

  • If your speaker or subwoofer is a sealed cabinet, most designers recommend that you lightly fill the inside with polyfill (pillow stuffing).  If you don't have polyfill, then you can line the walls with 1" - 1.5" thick light weight open cell foam (like acoustic foam) or fiberglass insulation.  You can also use 2-3" recyled denim insulation that can be bought at Home Depot.
  • It's okay to cover up your crossover with the polyfill, insulation, or foam.
  • If you're using a ported enclosure you should lightly fill the cabinet with polyfill and be sure not to block the ports.  If you do not have polyfill then line the walls with 1" - 1.5" thick open cell foam (like acoustic foam), 2" - 3" of denim insulation, or 2" - 3" thick poly batting.
  • Some of the speaker designers like to lines the walls of their ported enclosures with a 1" - 1.5" acoustic foam, and then lightly fill the remainder of the cabinet with polyfill.  If this is a required method, it will be listed at the top of the page under 'Assembly Notes'.

 

Links to Build Threads for this Speaker:

Frequently Asked Questions:

* Does the baffle come with roundovers?  Answer:  No.  If you really need roundovers, please send me an email and I can try to put them on the edges for you.

* What length do the ports have to be?  Answer:  The port that comes with the kit should be used at full length, no cutting.

* Do the woofers get wired in series or parallel?  Answer: They should be wired in parallel.

Also Purchased